提升管出口T型弯头压降特性的实验分析

在大型循环流化床装置上，以FCC催化剂颗粒为实验物料，针对提升管出口T型弯头用动态压力传感器测量了操作参数和结构尺寸变化对其压降的影响，系统地分析了T型弯头的压降特性。实验结果表明T型弯头的压降与颗粒浓度呈线性关系，与入口速度（提升表观气速）呈二次方关系；T型弯头出口管截面积的减小使得压降显著增大；T型弯头盲管高度的增加可使T型弯头的压降降低，但是当盲管高度增加到一定值时，压降减小不明显。盲管高度对压降的影响是由于盲管高度的增加改变了提升管上部压力的分布，使T型弯头入口压力减小，导致T型弯头的压降降低；同时盲管高度的增加也使提升管出口区域的负压约束区长度增加。盲管所形成的负压约束区构成了对提升管出口的约束作用，T型弯头的盲管高度越大负压约束区越长，约束作用越强。

Experimental analysis of T-abrupt exit’s pressure drop characteristics in riser

The pressure drop characteristics of T-abrupt exit of the riser were analyzed based on dynamic pressure data of gas-solids two-phase flow in a circulating fluidized bed equipment by using FCC catalyst particles, and varying the operation parameters and equipment dimensions. The pressure drop of T-abrupt exit changed linearly with inlet particle density, and quadratically with inlet gas velocity. It increased significantly with the decrease of outlet tube area of T-abrupt exit. Further, the pressure drop of T-abrupt exit decreased as blind tube length increased, but changed little above a specific length, because increased blind tube length changed the pressure distribution along the upper riser. As blind tube length increased, inlet pressure of T-abrupt exit decreased, hence pressure drop decreased. There was a negative pressure zone along the upper riser and blind tube, which constrained gas-solids two-phase flow in the riser. The longer the blind tube, the longer the negative pressure zone and the greater the constraint.